IB Physics Topic3 Thermal

What is the mass of carbon-12 that contains the same number of atoms as 14 g of silicon-28?

• 6 g

• 12 g

• 14 g

• 24 g

Carbon has a relative atomic mass of 12 and oxygen has a relative atomic mass of 16. A sample of 6 g of carbon has twice as many atoms as

• 32 g of oxygen.

• 8 g of oxygen.

• 4 g of oxygen.

• 3 g of oxygen.

Two objects are in thermal contact with each other. Which of the following will determine the direction of the transfer of thermal energy between the bodies?

• The mass of each body

• The area of contact between the bodies

• The specific heat capacity of each body

• The temperature of each body

Water at a temperature of 0 °C is kept in a thermally insulated container. A lump of ice, also at 0 °C, is placed in the water and completely submerged.

Which of the following is true in respect of both the net amount of ice that will melt and the change in temperature of the water?

• A

• B

• C

• D

Thermal energy is added at a constant rate to a substance which is solid at time t = 0. The graph shows the variation with t of the temperature T.

                                  

         Which of the statements are correct?

I.       The specific latent heat of fusion is greater than the specific latent heat of vaporization.

II.      The specific heat capacity of the solid is less than the specific heat capacity of the liquid.

• I only

• I and II

• II only

• Neither I nor II

A system consists of an ice cube placed in a cup of water. The system is thermally insulated from its surroundings. The water is originally at 20 °C. Which graph best shows the variation of total internal energy U of the system with time t?

• A

• B

• C

• D

An ice cube and an iceberg are both at a temperature of 0 °C. Which of the following is a correct comparison of the average random kinetic energy and the total kinetic energy of the molecules of the ice cube and the iceberg?

• A

• B

• C

• D

In the kinetic model of an ideal gas, it is assumed that

• the forces between the molecules of the gas and the container are always zero.

• the intermolecular potential energy of the molecules of the gas is constant.

• the kinetic energy of a given molecule of the gas is constant.

• the momentum of a given molecule of the gas is constant.

A gas is contained in a cylinder by a piston.

The gas is compressed rapidly by moving the piston in the direction shown. The best explanation for the resulting increase in temperature of the gas is that the molecules of the gas gain kinetic energy

• from the moving piston.

• by colliding more frequently with each other.

• by being pushed closer together.

• by colliding more frequently with the walls of the cylinder.

The volume of an ideal gas in a container is increased at constant temperature.

Which of the following statements is/are correct about the molecules of the gas?

I.       Their speed remains constant.

II.      The frequency of collisions of molecules with unit area of the container wall decreases.

III.     The force between them decreases.

• I only

• I and II only

• I and III only

• II and III only